1. Field of the Invention
The present invention relates to a hinge construction in which the hinge components are concealed from view when the door to which the hinge is attached is closed.
2. Description of the Prior Art
Hinges have been utilized to allow doors to be rotated relative to door frames for centuries. In conventional commercial building construction the predominant form of hinge construction employs a pair of hinge plates which each terminate in knuckles along one of their edges. The knuckles of the two hinge plates are interleaved with each other and define within their confines a cylindrical passage that receives a hinge pin. One of the hinge plates is attached to the edge of a door, while the other hinge plate is attached to the doorjamb or frame in alignment with the first hinge plate. Very typically two, three, or even more such hinges are provided to install a door in a door frame.
Conventional hinges of the type described have several significant disadvantages. When the hinge plates are attached to the door and to the frame to allow a door to open outwardly, there is a significant security risk. Unauthorized intrusion into the enclosure is quite easy even if the door is locked since the hinge knuckles and hinge pin are exposed. All that is required for an intruder to gain access to the enclosure is to drive the hinge pin out from its confines within the knuckles, thus allowing the door to separate from the jamb.
For this reason virtually all exterior doors of dwellings are hinged to open inwardly so that the hinge pins are not accessible from outside the building. However, inwardly opening doors are impractical for buildings such as garages, storage rooms, and other enclosures in which there is insufficient room on the inside for a door to swing inwardly. As a consequence, such structures are always vulnerable to unauthorized intrusion due to the construction of the hinges that hold the doors in place.
A further disadvantage of conventional hinge construction is that the exposed hinge elements must be fabricated of metal, usually steel, in order to be of sufficient durability to withstand long-term use. Iron or steel door hinges of this type, though strong enough to last for many years, are susceptible to rust. Even when hinges such as this are painted, the rust bleeds through and creates an unsightly discoloration not only on the hinge itself, but also on nearby door and frame surfaces.
Various hinge mechanisms have been designed to provide a hinge that is totally concealed from view when the door is closed. There are several advantages to the use of a concealed hinge. A hinge in which the components are totally concealed within the door frame and within the door when the door is closed offers no opportunity for tampering with the hinge from either side of the door. Thus, a hidden or concealed hinge offers significant security advantages over a conventional hinge having a hinge pin that passes through interleaved knuckles, particularly if the door opens outwardly.
A further advantage of concealing the component parts of a hinge is that even if there is some surface degradation to the hinge components, such as rust, the surface discolorations will be concealed from view when the door is closed. Moreover, since the hinge is concealed from view when the door is closed, it is also protected from the elements to a very significant extent. As a consequence, there will be less of a tendency for the hinge components to rust and discolor, since they are, to a large extent, protected within the structure of the door and door frame.
The biggest problem with past attempts to provide hidden or concealed hinges is that the construction of such devices has heretofore required such large cavities within a door and door frame that conventional concealed hinges cannot be utilized on standard doors if the doors are to fully open. To the contrary, conventional concealed hinges require cavities that are often wider than the standard one and three-eighths inch door that is used in most residential construction. As a consequence, the use of concealed hinges, as a practical matter, has only been possible with nonstandard doors of considerable thickness.
A further disadvantage of conventional concealed hinges is that the cavities that must be formed in the door and door frame require wide undercuts, and thus cannot be created using conventional cylindrical drill bits or convention sawtooth attachments for drills, such as are utilized in forming cylindrical doorknob and lock bolt openings in doors. Quite to the contrary, the concealed hinges of the types that have been previously devised require arcuately-shaped cavities in the door and in the jamb that can only be created with considerable skill and time.